Why do cataracts cause vision loss?

Your eye works like a camera. A camera needs a lens to focus an image. But when the lens is dirty or cloudy, the camera can’t take a good, clear picture.

It’s the same with your eyes. Your eye lens focuses rays of light on the nerve tissue at the back of your eye (the retina). The retina then transmits a clear image to your brain. But when a cataract clouds your eye’s lens, light rays don’t pass through as well and the retina cannot transmit a good picture.

About one in six Americans age 40 and older will get a cataract. By age 80, more than half will have a cataract. Because everyone is different, some people may not notice a large change in their eyesight. Others will find it a challenge to enjoy even the simplest tasks and may find it harder and harder to stay independent.

Light passes through a normal eye
without anything blocking its way.

When the lens of your eye becomes cloudy,
the cataract prevents you from seeing clearly
by preventing enough light from passing through.